
    <!DOCTYPE html>
    <html lang="zh-CN">
    <head>
      <meta charset="UTF-8">
      <meta name="viewport" content="width=device-width, initial-scale=1.0">
      <title>高效任务调度与并发流 - 交互式测验</title>
      <style>
        @import url('https://fonts.googleapis.com/css2?family=Noto+Sans+SC:wght@400;500;700&display=swap');
        
        body {
          font-family: 'Noto Sans SC', sans-serif;
          background-color: #f4f7f9;
          color: #333;
          display: flex;
          justify-content: center;
          align-items: center;
          min-height: 100vh;
          margin: 0;
          padding: 20px;
          box-sizing: border-box;
        }
        
        .main-wrapper {
            position: relative;
            width: 100%;
            max-width: 900px; /* Wider to accommodate buttons */
            display: flex;
            justify-content: center;
            align-items: center;
        }

        .quiz-container {
          background-color: #ffffff;
          border-radius: 16px;
          box-shadow: 0 8px 32px rgba(0, 0, 0, 0.1);
          width: 100%;
          max-width: 700px;
          overflow: hidden;
          z-index: 10;
        }

        .quiz-header {
          background-color: #4a90e2;
          color: white;
          padding: 20px 30px;
          text-align: center;
        }

        .quiz-header h1 {
          margin: 0;
          font-size: 24px;
          font-weight: 700;
        }
        
        .quiz-header p {
            margin: 5px 0 0;
            font-size: 14px;
            opacity: 0.9;
        }

        .quiz-body {
          padding: 30px;
        }

        .progress-bar {
            display: none; /* 隐藏进度条 */
            width: 100%;
            background-color: #e0e0e0;
            border-radius: 5px;
            height: 10px;
            margin-bottom: 20px;
        }

        #progress-indicator {
            height: 100%;
            width: 0%;
            background-color: #4caf50;
            border-radius: 5px;
            transition: width 0.3s ease;
        }

        #question-container {
          margin-bottom: 20px;
        }

        #question-text {
          font-size: 18px;
          font-weight: 500;
          line-height: 1.6;
          margin-bottom: 25px;
        }

        .options-list {
          list-style: none;
          padding: 0;
          margin: 0;
        }

        .option-item {
          background-color: #f8f9fa;
          border: 1px solid #dee2e6;
          border-radius: 8px;
          padding: 15px;
          margin-bottom: 12px;
          cursor: pointer;
          transition: background-color 0.2s ease, border-color 0.2s ease;
        }

        .option-item:hover {
          background-color: #e9ecef;
        }
        
        .option-item.selected {
            background-color: #d1e7fd;
            border-color: #4a90e2;
        }

        .quiz-footer {
          padding: 20px 30px;
          display: flex;
          justify-content: space-between; /* 将按钮分布在两侧 */
          align-items: center;
          min-height: 65px; /* Reserve space */
        }

        .nav-btn {
          background-color: #4a90e2;
          color: white;
          border: none;
          border-radius: 8px;
          padding: 10px 20px;
          font-size: 16px;
          font-weight: 500;
          cursor: pointer;
          transition: background-color 0.2s ease, transform 0.2s ease;
          box-shadow: 0 4px 12px rgba(0,0,0,0.15);
        }
        
        #next-btn {
            background-color: #28a745;
        }

        .nav-btn:hover {
          background-color: #357abd;
          transform: scale(1.05);
        }
        
        .nav-btn:disabled {
            background-color: #a0c3e8;
            cursor: not-allowed;
            opacity: 0.7;
        }

        #result-container {
            border-top: 1px solid #eee;
        }
        
        .result-box {
            border-radius: 8px;
            padding: 20px;
            margin-top: 20px;
        }
        
        .result-box.correct {
            background-color: #d4edda;
            border: 1px solid #c3e6cb;
            color: #155724;
        }

        .result-box.incorrect {
            background-color: #f8d7da;
            border: 1px solid #f5c6cb;
            color: #721c24;
        }
        
        .result-box h3 {
            margin-top: 0;
        }

        .explanation-text {
            margin-top: 15px;
            line-height: 1.7;
        }
        
        .source-text {
            font-style: italic;
            font-size: 14px;
            margin-top: 15px;
            color: #555;
        }

        
        .final-score-container {
            padding: 40px;
            text-align: center;
        }
        .final-score-container h2 {
            margin-top: 0;
            margin-bottom: 30px;
        }
        .score-summary {
            display: flex;
            justify-content: center;
            gap: 20px;
            margin-bottom: 40px;
            flex-wrap: wrap;
        }
        .score-card {
            background-color: #f8f9fa;
            border-radius: 12px;
            padding: 20px;
            width: 180px;
            box-shadow: 0 4px 12px rgba(0,0,0,0.05);
            border: 1px solid #e9ecef;
        }
        .score-card h3 {
            margin: 0 0 10px;
            font-size: 16px;
            font-weight: 500;
            color: #555;
        }
        .score-card p {
            margin: 0;
            font-size: 28px;
            font-weight: 700;
            color: #333;
        }
        .score-details table {
            width: 100%;
            font-size: 16px;
        }
        .score-details td {
            padding: 4px 0;
        }
        .score-details td:last-child {
            text-align: right;
            font-weight: 700;
        }
        .report-actions button {
            background-color: #fff;
            border: 1px solid #ccc;
            border-radius: 8px;
            padding: 12px 25px;
            font-size: 16px;
            cursor: pointer;
            margin: 0 10px;
            transition: background-color 0.2s ease, border-color 0.2s ease, transform 0.2s ease;
        }
        .report-actions button:hover {
            background-color: #f1f1f1;
            border-color: #bbb;
            transform: translateY(-2px);
        }
        .report-actions button.primary {
            background-color: #28a745;
            color: white;
            border-color: #28a745;
        }
        .report-actions button.primary:hover {
            background-color: #218838;
        }
        
        .hint-container {
            background-color: #e0f7fa;
            border: 1px solid #b2ebf2;
            border-radius: 8px;
            padding: 15px;
            margin-top: 20px;
            color: #006064;
            font-size: 15px;
            line-height: 1.6;
            display: none; /* 默认隐藏 */
        }
      </style>
    </head>
    <body>
      <div class="main-wrapper">
          <div class="quiz-container">
            <div class="quiz-header">
              <h1>高效任务调度与并发流 - 交互式测验</h1>
              <p>检验你对文档内容的理解程度</p>
            </div>
            <div id="quiz-content">
                <div class="quiz-body">
                    <div class="progress-bar">
                        <div id="progress-indicator"></div>
                    </div>
                    <div id="question-container">
                      <p id="question-text"></p>
                      <ul class="options-list" id="options-list"></ul>
                    </div>
                    <div id="result-container"></div>
                    <div id="hint-container" class="hint-container"></div>
                </div>
                <div class="quiz-footer" id="quiz-footer">
                  <button id="prev-btn" class="nav-btn">上一题</button>
                  <button id="hint-btn" class="nav-btn" style="background-color: #ffc107; color: #333; box-shadow: 0 4px 12px rgba(255,193,7,0.3);">提示</button>
                  <button id="next-btn" class="nav-btn">下一题</button>
                </div>
            </div>
          </div>
      </div>

      <script>
        const quizData = [
  {
    "question": "根据文档，使用线程池（如 `ThreadPoolExecutor`）管理任务的一个主要好处是什么？",
    "options": [
      "它通过复用线程来减少创建和销毁线程的开销。",
      "它保证任务严格按照提交的顺序执行。",
      "它会自动将单个任务分解为多个子任务并行处理。",
      "它能完全消除在并发编程中对同步锁的需求。"
    ],
    "correctAnswerIndex": 0,
    "explanation": "线程池的核心优势在于线程复用。通过维护一个固定或可变大小的线程池，系统可以避免为每个新任务都创建和销毁线程所带来的性能开销和资源消耗，同时也能防止因无限制创建线程而耗尽系统资源。",
    "source": "文档中「1.1 线程池与任务调度」部分",
    "hint": "文档提到线程池通过复用线程来减少了什么开销？"
  },
  {
    "question": "Java的并行流 (`parallelStream()`) 在底层默认使用哪个框架来实现任务的并行处理？",
    "options": [
      "一个由开发者自定义的 `ExecutorService`。",
      "一个 `ScheduledThreadPoolExecutor`。",
      "一个 `ForkJoinPool`。",
      "操作系统内核的本地线程调度器。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "并行流的设计是基于分治（Divide and Conquer）策略的，它默认利用 `ForkJoinPool` 来高效地调度和执行被拆分后的子任务。`ForkJoinPool` 特别适合这种计算密集型且可分解的任务，它通过工作窃取算法来最大化CPU利用率。",
    "source": "文档中「2.1 并行流的工作原理」部分",
    "hint": "文档中提到并行流会自动利用什么“池”来实现并行处理？"
  },
  {
    "question": "在什么情况下，使用并行流 (`parallelStream()`) 反而可能会导致性能下降？",
    "options": [
      "处理一个非常庞大的数据集，且每个元素的操作都相互独立。",
      "当程序运行在拥有多个CPU核心的服务器上。",
      "当操作的数据集非常小，导致线程调度和结果合并的开销超过了计算本身。",
      "当流操作中不包含任何共享的可变状态时。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "并行化并非没有成本。它涉及到数据分区、任务调度和最终结果合并等额外开销。对于小规模数据集或操作本身开销极低的任务，这些固定开销可能远大于顺序执行所节省的时间，从而导致整体性能不升反降。",
    "source": "文档中「2.2 并行流的性能与适用场景」部分",
    "hint": "文档中提到对于小规模数据集，使用并行流可能会增加什么“额外的开销”？"
  },
  {
    "question": "文档中提到的并行流的“副作用问题”（Side-effect issues）指的是什么？",
    "options": [
      "指在流操作中修改了某个共享的可变状态，可能引发线程安全问题。",
      "指并行处理时，过多的日志输出导致性能瓶颈。",
      "指为了拆分数据而消耗了额外的系统内存。",
      "指流操作中的Lambda表达式无法正确抛出和处理已检查异常。"
    ],
    "correctAnswerIndex": 0,
    "explanation": "副作用是指一个操作除了返回结果外，还修改了外部系统的状态，例如修改一个共享变量。在并行流中，多个线程同时执行带有副作用的操作，如果没有正确的同步措施，就会导致数据竞争和不确定的结果，这是并行编程中需要极力避免的。",
    "source": "文档中「2.3 并行流的限制与优化」部分",
    "hint": "当多个线程共享同一个变量或状态时，并行流可能会引发什么问题？"
  },
  {
    "question": "根据文档「1.2 任务调度策略」，以下哪一项不属于文中提到的高效任务调度策略？",
    "options": [
      "负载均衡 (Load Balancing)",
      "先进先出调度 (FIFO Scheduling)",
      "优先级调度 (Priority Scheduling)",
      "动态调整线程池大小 (Dynamic Sizing)"
    ],
    "correctAnswerIndex": 1,
    "explanation": "文档在「1.2 任务调度策略」一节中明确列举了三种策略：负载均衡、优先级调度和动态调整线程池大小。虽然先进先出（FIFO）是一种常见的调度方式，但该文档并未将其作为提升并发系统效率的核心策略之一进行讨论。",
    "source": "文档中「1.2 任务调度策略」部分",
    "hint": "请仔细回顾文档中提到的三种具体的任务调度策略，并找出选项中未被提及的一项。"
  },
  {
    "question": "并行流底层的 `ForkJoinPool` 采用“工作窃取”（Work-stealing）算法，该算法的主要目标是什么？",
    "options": [
      "确保高优先级的任务总是最先被执行。",
      "让空闲的线程从繁忙线程的任务队列中“窃取”任务来执行，以提高CPU利用率。",
      "在任务执行前，预先分配好所有需要的内存资源。",
      "强制将一个大任务均匀地分割成大小完全相等的子任务。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "工作窃取算法是 `ForkJoinPool` 的核心机制之一。当池中的某个线程完成了自己队列中的所有任务后，它不会保持空闲，而是会去查看其他线程的任务队列，如果发现有未完成的任务，就会“窃取”一个来执行。这能有效减少线程空闲时间，最大化地利用多核CPU资源。",
    "source": "文档中「2.1 并行流的工作原理」部分",
    "hint": "文档提到 `ForkJoinPool` 能通过工作窃取算法动态调度哪种线程？"
  },
  {
    "question": "文档最后一个示例展示了将 `ExecutorService` 与 `parallelStream()` 结合使用的模式。这种做法的主要优势是什么？",
    "options": [
      "它能够完全避免使用 `Future` 对象，从而简化异步编程模型。",
      "这是在Java中使用 `parallelStream()` 的唯一标准方法。",
      "它通过在一个专用线程池中管理宏观任务，同时在任务内部利用并行流处理数据，实现了更精细的并发控制。",
      "它可以让 `parallelStream()` 摆脱对默认 `ForkJoinPool` 的依赖，运行得更快。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "这种模式结合了两种并发模型的优点。外层的 `ExecutorService` 负责管理和调度几个大的、独立的任务单元，避免了所有并行操作都挤占在同一个公共的 `ForkJoinPool` 中。而每个任务单元内部又可以利用 `parallelStream()` 来加速其自身的数据密集型计算。这提供了一种分层的、更可控的并发策略。",
    "source": "文档中「3. 高效任务调度与并发流的结合」部分",
    "hint": "思考一下，为什么示例代码要先用 `ExecutorService` 提交任务，然后在任务内部再使用 `parallelStream`？"
  }
];
        console.log("Quiz Data:", JSON.parse(JSON.stringify(quizData))); // 添加这行用于调试，以可展开的JSON格式输出
        
        let currentQuestionIndex = 0;
        let score = 0;
        // 存储每个问题的回答状态
        const userAnswers = new Array(quizData.length).fill(null); 

        const questionTextEl = document.getElementById('question-text');
        const optionsListEl = document.getElementById('options-list');
        const resultContainerEl = document.getElementById('result-container');
        const quizContentEl = document.getElementById('quiz-content');
        const progressIndicatorEl = document.getElementById('progress-indicator');
        const prevBtn = document.getElementById('prev-btn');
        const nextBtn = document.getElementById('next-btn');
        const hintBtn = document.getElementById('hint-btn');
        const hintContainerEl = document.getElementById('hint-container');

        function loadQuestion() {
          resultContainerEl.innerHTML = '';
          optionsListEl.innerHTML = '';
          hintContainerEl.style.display = 'none'; // 隐藏提示
          
          if (currentQuestionIndex >= quizData.length) {
            showFinalScore();
            return;
          }

          updateProgress();

          const currentQuestion = quizData[currentQuestionIndex];
          questionTextEl.textContent = `(${currentQuestionIndex + 1}/${quizData.length}) ${currentQuestion.question}`;
          
          currentQuestion.options.forEach((optionText, index) => {
            const li = document.createElement('li');
            li.className = 'option-item';
            li.textContent = optionText;
            li.dataset.index = index; // Store index in a data attribute
            // 如果这道题已经回答过，恢复状态
            if (userAnswers[currentQuestionIndex] !== null) {
                if (index === userAnswers[currentQuestionIndex]) {
                    li.classList.add('selected');
                }
            }
            optionsListEl.appendChild(li);
          });

          // 如果已经回答过，直接显示结果
          if (userAnswers[currentQuestionIndex] !== null) {
              const isCorrect = userAnswers[currentQuestionIndex] === currentQuestion.correctAnswerIndex;
              showResult(isCorrect, currentQuestion);
          }
          
          updateNavigationButtons();
          updateProgress();
        }

        function selectOption(optionIndex) {
            userAnswers[currentQuestionIndex] = optionIndex;
            const currentQuestion = quizData[currentQuestionIndex];
            const isCorrect = optionIndex === currentQuestion.correctAnswerIndex;

            // 重新计算分数
            score = userAnswers.reduce((acc, answer, index) => {
                return answer === quizData[index].correctAnswerIndex ? acc + 1 : acc;
            }, 0);

            showResult(isCorrect, currentQuestion);
            updateNavigationButtons();
        }
        
        function updateProgress() {
            const answeredQuestions = userAnswers.filter(answer => answer !== null).length;
            const progressPercentage = (answeredQuestions / quizData.length) * 100;
            progressIndicatorEl.style.width = `${progressPercentage}%`;
        }
        
        function updateNavigationButtons() {
            prevBtn.style.display = 'block';
            nextBtn.style.display = 'block';
            hintBtn.style.display = 'block'; // 显示提示按钮

            prevBtn.disabled = currentQuestionIndex === 0;
            nextBtn.disabled = false; // 最后一题时，下一题按钮不禁用，而是用于显示报告
            nextBtn.textContent = (currentQuestionIndex === quizData.length - 1) ? '查看报告' : '下一题';
            
            // 如果当前问题没有提示，则禁用提示按钮并隐藏提示内容
            if (!quizData[currentQuestionIndex].hint) {
                hintBtn.disabled = true;
                hintContainerEl.style.display = 'none';
                hintContainerEl.textContent = ''; // 清除旧的提示内容
            } else {
                hintBtn.disabled = false;
            }
        }

        function showResult(isCorrect, questionData) {
            resultContainerEl.innerHTML = ''; // 清空之前的结果
            const resultBox = document.createElement('div');
            resultBox.className = `result-box ${isCorrect ? 'correct' : 'incorrect'}`;
            
            let html = `<h3>${isCorrect ? '回答正确！' : '回答错误'}</h3>`;
            if (!isCorrect) {
                html += `<p><strong>正确答案是：</strong> ${questionData.options[questionData.correctAnswerIndex]}</p>`;
            }
            html += `<div class="explanation-text">${questionData.explanation}</div>`;
            html += `<div class="source-text">来源: ${questionData.source}</div>`;
            
            resultBox.innerHTML = html;
            resultContainerEl.appendChild(resultBox);

            // 禁用所有选项的点击事件，并高亮正确/错误答案
            Array.from(optionsListEl.children).forEach((child, index) => {
                child.style.pointerEvents = 'none';
                // 高亮正确答案
                if (index === questionData.correctAnswerIndex) {
                    child.classList.add('correct'); // 需要添加CSS样式
                    child.style.backgroundColor = '#d4edda';
                    child.style.borderColor = '#c3e6cb';
                }
                // 如果选错了，高亮错误选项
                if (!isCorrect && index === userAnswers[currentQuestionIndex]) {
                    child.classList.add('incorrect'); // 需要添加CSS样式
                    child.style.backgroundColor = '#f8d7da';
                    child.style.borderColor = '#f5c6cb';
                }
            });
        }

        function goToNextQuestion() {
            if (currentQuestionIndex < quizData.length - 1) {
                currentQuestionIndex++;
                loadQuestion();
            } else {
                showFinalScore();
            }
        }

        function goToPreviousQuestion() {
            if (currentQuestionIndex > 0) {
                currentQuestionIndex--;
                loadQuestion();
            }
        }
        
        function showHint() {
            const currentQuestion = quizData[currentQuestionIndex];
            if (currentQuestion.hint) {
                hintContainerEl.textContent = currentQuestion.hint;
                hintContainerEl.style.display = 'block';
            } else {
                hintContainerEl.style.display = 'none';
            }
        }

        function showFinalScore() {
            document.querySelector('.quiz-body').style.display = 'none';
            document.getElementById('quiz-footer').style.display = 'none';

            const correctCount = score;
            const totalQuestions = quizData.length;
            const answeredCount = userAnswers.filter(a => a !== null).length;
            const wrongCount = answeredCount - correctCount;
            const skippedCount = totalQuestions - answeredCount;
            const accuracy = totalQuestions > 0 ? Math.round((correctCount / totalQuestions) * 100) : 0;
            const errorRate = totalQuestions > 0 ? Math.round((wrongCount / totalQuestions) * 100) : 0;

            const finalScoreHtml =
                '<div class="final-score-container">' +
                '<h2>答题报告</h2>' +
                '<div class="score-summary">' +
                '<div class="score-card">' +
                '<h3>得分</h3>' +
                '<p>' + correctCount + ' / ' + totalQuestions + '</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>正确率</h3>' +
                '<p>' + accuracy + '%</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>错误率</h3>' +
                '<p>' + errorRate + '%</p>' +
                '</div>' +
                '<div class="score-card score-details">' +
                '<table>' +
                '<tr><td>正确</td><td>' + correctCount + '</td></tr>' +
                '<tr><td>错误</td><td>' + wrongCount + '</td></tr>' +
                '<tr><td>未答</td><td>' + skippedCount + '</td></tr>' +
                '</table>' +
                '</div>' +
                '</div>' +
                '<div class="report-actions">' +
                '<button id="review-btn">回顾测验</button>' +
                '<button class="primary" onclick="location.reload()">再试一次</button>' +
                '</div>' +
                '</div>';

            let reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }
            quizContentEl.insertAdjacentHTML('beforeend', finalScoreHtml);
            document.getElementById('review-btn').addEventListener('click', reviewQuiz);
        }

        function reviewQuiz() {
            const reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }

            document.querySelector('.quiz-body').style.display = 'block';
            document.getElementById('quiz-footer').style.display = 'flex';
            
            currentQuestionIndex = 0;
            loadQuestion();
            updateNavigationButtons(); // Ensure nav buttons are correctly displayed
        }

        // Event Delegation for options
        optionsListEl.addEventListener('click', (event) => {
            if (event.target && event.target.matches('li.option-item')) {
                // Check if the question has already been answered
                if (userAnswers[currentQuestionIndex] === null) {
                    const selectedIndex = parseInt(event.target.dataset.index, 10);
                    selectOption(selectedIndex);
                }
            }
        });

        prevBtn.addEventListener('click', goToPreviousQuestion);
        nextBtn.addEventListener('click', goToNextQuestion);
        hintBtn.addEventListener('click', showHint);
        
        // 初始加载
        loadQuestion();
      </script>
    </body>
    </html>
  